Changing Epidemiology of Invasive Pneumococcal Disease due to Conjugate Vaccine Serotypes in Toronto, Canada After Introduction of a Routine Pediatric PCV13 Program

BACKGROUND: In Ontario a publicly funded PCV7 infant program (3 + 1 schedule), was introduced in 1/2005, PCV10 in 10/2009 and PCV13 in 11/2010 (2 + 1 schedule with catch-up to 35m). TIBDN performs population-based surveillance for invasive pneumococcal disease (IPD) in Toronto/Peel to evaluate program impact. METHODS: IPD cases are reported to a central office and one isolate/case is serotyped. Demographic/ clinical data are collected by chart review and patient/physician interview. RESULTS: From 1/1995–5/2017, 9727 IPD cases have been identified. Among 910 IPD cases since 2015, 109 (12%) were aged <15y, 376 (41%) 15–64y and 425 (41%) aged ≥65y; 57 (7%) were due to serotypes (STs) included in PCV7, 188 (24%) due to STs in PCV13 but not PCV7, 228 (30%) due to STs in PPV23 but not PCVs, and 295 (38%) due to non-vaccine STs (142 isolates not available/not yet typed). The incidence of IPD in 2016 was 4.78/100000 in children and 5.68/100000 in adults (44% and 32% reduction since 2008/9 respectively. Since 1/1/2015, there has been no IPD due to PCV7 STs in children. In adults, 57 episodes include 19 of ST4, 13 ST19F, 8 ST14, 7 ST6B, 5 ST9V, 3ST18C and 2 ST23F. The median age of patients was 64.5y (range 28–98), 37 were male; 67% had an underlying illness. PCV7 ST cases were more likely to be associated with group housing than other cases (12/45, 21%, v 47/644, 7%, P < .01); 6/19 cases of ST4 were associated with a single homeless shelter, and 3/8 due to ST14 occurred in one nursing home. Of 188 episodes due to PCV13/not PCV7 serotypes, 87 were due to ST3, 72 ST19A, 16 ST7F, 11 ST6A, and 1 each due to ST1 and ST5. 22 cases occurred in children (12 ST3, 9 ST19A, 1 ST7F): 1 child refused consent, and 1 had missing data; 4 were vaccine ineligible; 2 unvaccinated; 9 incompletely vaccinated; and 5 vaccine failures (2 ST3, 3 ST19A). The most recent case of pediatric IPD due to ST19A was in Aug/2016; both pediatric cases to date in 2017 are ST3. The incidence of IPD due to STs 19A and 3 over time in children and adults is shown in the Figures. CONCLUSION: Since PCV13-program implementation, IPD due to PCV7 STs has decreased to zero among children and remains low in adults, although clusters in communal living situations may be emerging. IPD due to ST19A has declined dramatically. IPD incidence due to ST3 has not changed significantly since 1995. DISCLOSURES: All authors: No reported disclosures.